|WKP|
Definition: A tendon or sinew is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension.
Tendons are similar to ligaments; both are made of collagen. Ligaments join one bone to another bone, while tendons connect muscle to bone.
They are associated to a tendon sheath .
Pathology : tendinopathies
injury
rupture
inflammation : tendinitis
alteration / degenerescence : tendinosis
See also
locomotory (...)

WKP
A tendon sheath is a layer of synovial membrane / synovium around a tendon.
Function
It permits the tendon to stretch and not adhere to the surrounding fascia.
Structure
It has two layers:
synovial sheath - synovial membrane - synovium > tenosynovium
fibrous tendon sheath
Pathology
inflammation : tenosynovitis
tumors
fibroma of the tendon sheath
See also
tendon
locomotory (...)

See also
giant cell tumor of the tendon sheath (GCT-TS)
References
Multifocal giant cell tumor of the tendon sheath occuring at different localizations of the same tendon of a finger: a case report and review of the literature. Altaykan A, Yildiz K, Hapa O, Cukur S. Eklem Hastalik Cerrahisi. 2009;20(2):119-23. PMID: #19619117# [Free]